1. Field of the Invention
The invention relates to a slotless motor with coils which form revolving magnetic fields in stator cores having no slots.
2. DESCRIPTION OF THE BACKGROUND
A slotless motor can suppress electromagnetic noise and torque ripples of harmonic magnetic fluxes caused by stator slots. Because of that suppression ability, it is hoped to utilize the slotless motor for apparatuses in which low-noise and low-torque ripples are needed. The slotless motor is disclosed in Japanese Laid-open Patent Application (Kokai) No. 1-252134 and Japanese Publication Patent Application (Kokoku), No. 57-21932.
By the way, in the slotless motor, a gap between a stator and a rotor has a great influence on the characteristics of the slotless motor. Generally, as leakage fluxes increase in response to the size of the gap, output torque falls and a power factor changes for the worse according to the size of the gap.
Accordingly, it is desirable that the gap be as small as possible.
However, in the slotless motor as described above, it was difficult to make the gap sufficiently small, because the stator coils were constructed in two layers.